This invention relates to circuit breakers, and, more particularly to a circuit breaker interface mechanism for an auxiliary switch accessory.
It is generally well known in the art of circuit breakers to provide a reset mechanism to reset a tripping device such as an accessory shunt trip or under voltage device. During quiescent operation, (i.e. when the circuit breaker contacts are closed to allow the flow of electrical current) the operating handle of an operating mechanism is in the “ON” position. To stop the current flow manually, the handle may be shifted to the “OFF” position thereby opening the electrical contacts. Upon attainment of a pre-determined condition (trip event), such as ground fault or overload, the operating mechanism of the circuit breaker will release the forces of the mechanism operating springs and release the operating handle to a tripped position between the “ON” position and the “OFF” position. Before the circuit breaker may be turned “ON”, the operating mechanism must be manually reset. This is accomplished by rotating the operating handle beyond the “OFF” position against the bias of the operating mechanism springs, thereby locking the operating mechanism in position.
The same mechanical forces used to direct the operating mechanism from the tripped position to the reset position are used to reset any attached accessories, such as a shunt trip actuator, auxiliary switch accessory, bell alarm or other type of accessory unit. However, as accessories are generally separate components mounted proximate to the operating mechanism, positional variations at the interface of the accessory and the circuit breaker operating mechanism are possible due to manufacturing tolerances. These positional variations can affect the resetting motion translated to the bell alarm switch or its components by not compensating for any over-travel resulting from the possible tolerance variations. Furthermore, a reliable interface mechanism between the circuit breaker and internal accessories is desired that will provide reliable actuation of the accessory switch to change a state thereof when the breaker changes state in either an “on”, “off”, or “trip” operation without robbing energy from the operating mechanism during the “off” to “on” operation, which is common with conventional accessory interface systems. Conventional accessory interface systems between the operating mechanism and accessories presently rely only on limited “take up” provided by the accessory switch. It is further desired that the switch also be field installable by the customer without violating UL requirements.